Siege of Ostia (1493)

The Siege of Ostia (1493) occurred when the Papal army of Juan Borgia the Younger and Guidobaldo da Montefeltro

Background
Following the election of Pope Alexander VI, Cardinal Giuliano Della Rovere left the Papal court in Rome for Naples, seeking to depose the Borgia pope. King Ferrante I of Naples had an axe to grind with Rome after Cardinal Ascanio Sforza, a member of the rival House of Sforza of Milan, was appointed Vice-Chancellor, and he took Della Rovere's side. In September 1492, Prince Alfonso of Naples led the Neapolitan navy to Ostia, sealing off Ostia and Porto; Rome was unable to import any goods, and the city began to starve. Pope Alexander decided to form a coalition of city-states against Naples, the Orsini, the Colonna, and Cardinal Della Rovere, and this alliance consisted of Mantua, Siena, Ferrara, Venice, and Milan. The Pope managed to broker peace with Naples when he had his son Joffre Borgia marry Princess Sancia of Naples, forcing Della Rovere to flee to France; he sought to enforce King Charles VIII of France's "divine right" to the Neapolitan throne, rather than confirm Prince Alfonso as the new king after Ferrante's death. In January 1493, the Pope stripped the traitorous Della Rovere of his archdiocese, and he ordered his son Juan Borgia the Younger and his second-in-command Guidobaldo da Montefeltro to take their men to Ostia, seize the port, and sack the palace.

Siege
The Papal army laid bridges over the moat on two sides of the castle, and they rushed a siege tower and a battering ram over the bridges. They also sent their fiercest fighters to climb latters over the walls at three points, and they took the hallways, trapping Della Rovere's men on the stairs, where they were slaughtered. Della Rovere had sailed to France before his fortress was conquered, but the victory was nonetheless a great one for the Papal army. Borgia handed the keys to the fortress to his father in Rome, angering Cardinal Ascanio Sforza, who saw the siege as a provocation against King Charles VIII of France.